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Annu Rev Biochem. 2017 Jun 20;86:485-514. doi: 10.1146/annurev-biochem-061516-044500.

A New Facet of Vitamin B12: Gene Regulation by Cobalamin-Based Photoreceptors.

Author information

1
Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain; email: padhu@iqfr.csic.es.
2
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
3
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158-2140; email: marco.jost@ucsf.edu.
4
Department of Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; email: cdrennan@mit.edu.
5
Departamento de Genética y Microbiología, Área de Genética, Unidad Asociada al Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; email: melias@um.es.

Abstract

Living organisms sense and respond to light, a crucial environmental factor, using photoreceptors, which rely on bound chromophores such as retinal, flavins, or linear tetrapyrroles for light sensing. The discovery of photoreceptors that sense light using 5'-deoxyadenosylcobalamin, a form of vitamin B12 that is best known as an enzyme cofactor, has expanded the number of known photoreceptor families and unveiled a new biological role of this vitamin. The prototype of these B12-dependent photoreceptors, the transcriptional repressor CarH, is widespread in bacteria and mediates light-dependent gene regulation in a photoprotective cellular response. CarH activity as a transcription factor relies on the modulation of its oligomeric state by 5'-deoxyadenosylcobalamin and light. This review surveys current knowledge about these B12-dependent photoreceptors, their distribution and mode of action, and the structural and photochemical basis of how they orchestrate signal transduction and control gene expression.

KEYWORDS:

CarH; chromophore; optogenetics; photochemistry; photoregulation; transcriptional repressor

[Indexed for MEDLINE]

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